I'm guessing it's a small suite in part of a larger property, based on what I've seen? Thanks

Here you go -

Bach batch, n. colloquial New Zealand term referring to secondary abode/ beach house temporary escape/ sanctuary/ water/ sand/ old furniture/ crayfish pots/ dried seaweed windswept/ smiling faces/ books/ surf/ broken paddle ski/ cards/ woodpiles/ barbeques chilly bins/ carefree/ childlike/ memories...

Above taken from this site:

http://www.nzbaches.co.nz/

Many Kiwis refer to their secondary homes/cottages as "baches". These can range from fancy to very basic facilities and decor. Rental pricing will depend on whether on not it is a hot locations and amenities offered.
Hope this helps.

Elizabeth - It's the same thing we call 'the cottage' here in Canada. (I think you're Canadian.)

Thanks all - now I understand (especially the "Cottage" descriptor Travellin because you're right - I'm Canadian).